With the increasing use of optical signals in telecommunications networks, the demand for high-bandwidth capable equipment for redirecting the transmission of optical signals within the network, such as N×N optical switches (where N is a positive whole number), multiplexers (i.e. an N×1 switch), demulitplexers (i.e., a 1×N switch) and the like, has increased. One type of optical switch converts an optical signal received on one optical port to the switch interface (e.g., an optical fiber end) to an electrical signal, redirects the signal electronically, and re-converts the electrical signal to an optical signal output on a desired optical port from the switch interface (e.g., another optical fiber end). Such optical switches are known as Optical Electrical Optical (OEO) switches. As may be appreciated, the bandwidth and switching speed capabilities of an OEO switch may be limited by the initial optical-to-electrical and subsequent electrical-to-optical signal conversions that are required.
A different approach to redirecting optical signals within the network is known that overcomes the limitations of OEOs by redirecting the signals in the optical domain eliminating the optical-to-electrical and electrical-to-optical signal conversions. Such all optical switches are known in the art as Optical Cross Connect (OXC) switches. One type of OXC utilizes moveable reflectors (e.g., mirrors) to provide for the redirection of optical signals within the free space of the switch interface (i.e. without optical fibers, waveguides or the like guiding transmission of the optical signals within the switch interface). Typically such switches employ at least a pair of reflectors that are moved to respective orientations in order to provide an optical pathway within the free-space of the switch interface between any one of a plurality of input ports to the switch interface and any one of a plurality of output ports from the switch interface.
As may be appreciated, an important parameter of reflective-type free space OXCs is how quickly the reflectors can be accurately positioned in the orientations required to direct an optical signal between the desired input and output optical ports. This in turn may depend upon a number of factors, including how far the reflectors must be moved from respective predetermined reference orientations to the required orientations. Other important parameters of reflective-type free space OXCs include the length of the optical pathway within the free space switch interface that an optical signal must traverse in order pass from one of the input ports to one of the output ports and the proximity of the optical inputs and outputs to the reflectors. As the distance between the reflectors and the inputs and outputs increases, there is less tolerance to alignment inaccuracies between the reflectors and the inputs and outputs.